if you want a dome, then 350 for a few minutes, then 325 for the rest. Otherwise 325 the whole time, and yes you'll probably need to cook for longer. I'm still experimenting, but my last batch I cooked at 350 for five minutes, then 325 for about 15. I guess it depends on your cupcakes. Then with the same batch of batter, I cooked at 325 the whole way. It took about five minutes longer, but they weren't as domed. Actually I had over-filled my cups, and the domed ones rose so fast they were neat and tidy, the flat one spilled over the edge because it rose before it had time to cook enough to hold it's shape. If I hadn't overfilled it would have been fine.